In this blog I will show you how to interface an Atari-style joystick to the Altera DE1 FPGA board running a Spectrum implementation, how to change the ROM to enable you to input some game-cheat pokes and a few games I eventually completed using this setup.
...continue reading "ZX Spectrum ROM mods"


In the last article I presented a different way of architecturally modelling a Zilog Z80 processor. It is time to do something really useful with it and what could be better than reliving the past for a moment? Let's recreate an old computer and load in and play some games!
...continue reading "ZX Spectrum on FPGA using A-Z80 CPU"

In the first post I described the sequencer, a circuit that provided discrete timing signals to space operations apart. In the second post I mentioned the Timing matrix that was run by these signals and orchestrated a dance of control signals in time.

This article is about making it all alive and kicking within an FPGA solution.
...continue reading "A Z80 : The Soul"


A-Z80 is a conceptual implementation of the venerable Zilog Z80 processor targeted to synthesize and run on a modern FPGA device. It differs from the existing (mostly Verilog) Z80 implementations in that it is designed from the ground-up through the schematics and low-level gates.
...continue reading "A Z80 From the Ground Up"